Wiredrawing lubrication

ABSTRACT

A CONCENTRATE FOR USE IN FORMING AN AQUEOUS WIREDRAWING LUBRICANT COMPRISING A MIXTURE OF SULPHATED SPERM OIL AND SULPHATED RAPESEED OIL. THE CONCENTRATE MAY BE MECHANICALLY DISPERSED IN THE WATER TO FORM THE LUBRICANT OR A SURFACTANT MAY BE INCLUDED IN THE CONCENTATE TO AID DISPERSION.

United States Patent 3,574,110 WIREDRAWING LUBRICATION Deryk F. G.Hampson, Wantage, and Mervyn R. White,

Didcot, England, assignors to Esso Research and Eng:- neering Company NoDrawing. Filed June 18, 1969, Ser. No. 834,555 Claims priority,application Great Britain, June 20, 1968, 29,390/68 Int. Cl. Cm 1/06,1/38 US Cl. 252-33 13 Claims ABSTRACT OF THE DISCLOSURE A concentratefor use in forming an aqueous wiredrawing lubricant comprising a mixtureof sulphated sperm oil and sulphated rapeseed oil. The concentrate maybe mechanically dispersed in the water to form the lubricant or asurfactant may be included in the concentrate to aid dispersion.

The present invention relates to the lubrication of wires which aresubjected to wiredrawing processes.

:Metal wire is made by drawing a rod or wire through a die or series ofdies of durable material which reduce the diameter of the wire whileelongating the wire and sometimes producing changes in the quality ofthe metal of the wire.

The frictional forces generated during wiredrawing are considerable andit is desirable to lubricate the passage of the wire through the die(s)in order to mitigate the frictional forces, avoid the generation ofexcessive heat in the die(s) which would adversely affect the die(s) andthe properties of the 'wire, and to ameliorate the degree of attritionof the wire and the die(s).

Usually the die(s) and the wire are immersed in a sump or bath oflubricant so that lubricant is available to the critical regions of eachdie and so that heat is quickly dissipated. Wires formed wholly ormainly of copper or materials having similar drawing characteristics areusually drawn through dies at relatively high speeds (for example, 3000feet per minute) consequently, the need to dissipate heat from the dieis important and water-based lubricants are used in order to make use ofthe high specific heat of water.

The water-based lubricants which have previously been used have includedan emulsion of a fatty oil such as rapeseed oil. These prior lubricantswere subject to a number of disadvantages such as poor emulsionstability, despite the presence of emulsifiers, and excessive formationof metallic soaps which trapped metal fines abraded from the wirecausing clogging or excessive wear of the die and producing adeleterious change in the composition of the emulsion. In addition, themetallic soaps and fines contaminated the lubricating emulsion forming ascum which impaired the properties of the emulsion and deposited on thesides of the sump, necessitating frequent cleaning of the sump withconsequent loss of through-put. Some previously-known aqueous emulsionsemulsions employed as wiredrawing lubricants also have been known toattack ferrous metal parts of the wiredrawing machine, causingcorrosion.

According to the present invention, a concentrate for making an aqueouswiredrawing lubricant comprises sulphated rapeseed oil and sulphatedspenm. oil.

By sulphated oil is meant the product obtained by treating the oil withrelatively concentrated sulphuric acid for several hours at temperaturesof from 0 C. to 40 C. to cause sulphation of the oils to take place atdouble bonds to form true sulphates rather than sulphonates. The 80content of such sulphates may range from 0.5 to 10 wt. percent dependingon the strength of the sulphuric ice acid, the nature of the oil and theconditions of treatment.

After sulphation, the oils are water-washed and then treated with a basesuch as ammonia or caustic soda solution until the pH is 6.5 to 10.0,preferably 7.0 to 9.5.

The compositions of suitable sulphated oils (as determined by themethods of analysis prescribed in Standard Methods of Analysis publishedby the Society of Leather Trade Chemists, The National Leather SellersCollege, 176 Tower Bridge Road, London, SE. 1.) are as follows,expressed in weight percentages on a basis of 100 wt. percent totalfatty matter by extraction:

TAB LE I Sulphated Sulphatcd sperm oil rapeseed oil Total fatty matterby extraction Combined S03 Neutral oil Free fatty acids, as oleic acidUnsaponifiable matter Total alkali, expressed as N aOH Generallyspeaking, the sulphated oils will comprise a certain amount of water,and typical ranges of compositions of each of the sulphated oils,expressed in weight percentages on a basis of 100 wt. percent sulphatedoil are as follows:

TABLE II Sulphated sulphated sperm oil rapeseed oil The pH of 10 vol.percent emulsions in water of both sulphated oils is from 7.5 to 9.5 ineach case.

The concentrate may comprise between 25 vol. percent and vol. percent ofsulphated rapeseed oil, the remainder being sulphated sperm oil.

Particularly preferred concentrates according to the invention compriseabout 50 vol. percent sulphated rapeseed oil, the remainder beingsulphated sperm oil.

Preferably, the free fatty acid content of the concentrate is below 3.0wt. percent expressed as oleic acid, and the wiredrawing properties ofthe aqueous emulsion of the concentrate are most satisfactory when thefree fatty acid of the concentrate is initially from 2.5 to 3.0 wt.percent expressed as oleic acid. The amount of free fatty acid in theconcentrate is determinable by the degree of sulphation andneutralisation during manufacture. The concentration of free fatty acidmay change during the wiredrawing operation, but it has been found thatthe fatty acid content of the concentrate before addition to the wateris important in obtaining the most advantageous results in thewiredrawing process.

The concentrates according to the invention are found to give aqueouswiredrawing lubricants having extremely good emulsion stability and longworking life without excessive formation of copper soaps. The scum andmetal fines deposition of previously-known lubricants are substantiallyabsent, or mitigated to an unprecedented extent. Another benefit of thewiredrawing lubricant made from the concentrate from the operativespoint of view is that substantially no unpleasant odour is produced evenunder arduous working conditions.

The invention also includes an aqueous wiredrawing lubricant comprisinga major proportion of water and a minor proportion, such as 1 to 20 vol.percent, of the concentrate described in the preceding paragraphs.Usually, the lubricant will comprise 2 to 9 vol. percent of theconcentrate and 5 to 7 vol. percent is a preferred range ofcompositions. It is to be understood, however, that during the use ofthe wiredrawing lubricant, the concentrations of the sulphated rapeseeedand sperm oils will change and additions of concentrate to the lubricantto restore the preferred range of compositions will be desirable.

The aqueous wiredrawing lubricant may be made simply by adding theconcentrate to water in the desired proportions, and stirring oragitating until satisfactory dispersion is effected: generally speaking,the better the degree of dispersion, the greater will be the stabilityof the emulsion, and emulsion stability is an important factor inensuring satisfactory lubrication.

The stirring of the concentrate in the water may be performed manuallyby means of a paddle, or mechanically by means of an industrial stirrerof any type. In the case of manual stirring, the degree of dispersiondepends on the conscientiousness of the personnel to a great extent:where the operatives cannot be relied upon to give the concentrate asuitable degree of dispersion, it may be more attractive in awiredrawing plant to rely on physicochemical means of dispersion ratherthan to employ a mechanical stirrer which occupies floor space, and dueto intermittent usage, would represent uneconomically deployed capital.To this end a surfactant may be incorporated in the concentrate. Asuitable surfactant is the sulphonated castor oil product commerciallyavailable under the name Turkey Red oil (hereinafter designated TRO).TRO mixes readily with the sulphated oils of the concentrate, and theconcentrate of the invention may comprise 3 to 7 volume percent of TROor any other suitable surfactant: a preferred concentration of thesurfactant would be about vol. percent.

The invention further includes a method of drawing wire in which a wirelubricant with an aqueous wiredrawing lubricant formed from theconcentrate hereinabove described is drawn through one or more dies.

In addition, the invention includes wire drawn by the method of thepreceding paragraph.

The invention will now be further illustrated by reference to some testscarried out on a number of aqueous wiredrawing lubricants:

Sulphated rapeseed and sperm oils were prepared by treating the oilseither separately or in combination with 96% sulphuric acid for severalhours at between 0 C. and 40 C. in agitated tanks. The contents of thetanks were allowed to separate into an upper oily layer and a lower acidlayer, the latter being run off. The oily layer was then washed withwater, and caustic soda solution added until the pH of a vol. percentemulsion in water was from 6.5 to 9.5.

The properties of the sulphated oils were approximately as follows:

TAB LE III Sulphated Sulphated sperm oil rapeseed oil Total fatty matterby extraction wt. percent 87. 5 86. 0 Free fatty acids (wt. percent asoleic aeid) 2. 0-3. 0 2. 0-3. 0 Total alkali (as NaOH) wt percent 0. 50.2 Water, wt. percent 8. 0 3 Combined S03. wt. percent 1. 5 .2Unsaponifiable matter. wt. percent 7. 7

Neutral oil content, wt. percent.

The lubricant was a 6 volume percent emulsion of the above-specifiedsulphated sperm oil in water, similar to known commercially-usedwiredrawing lubricants.

After a short operating time, a scum of copper fines appeared on thesurface of the lubricant and a buildup 4 of copper soaps and copperfines was apparent on the dies and the sides of the tank containing thelubricant, rendering the lubricant unsuitable for further use. Inaddition, the sulphated sperm oil began to de-emulsify, thus impairingits remaining lubricating properties.

TEST 2 The wire was lubricated with a 6 volume percent emulsion of thesulphated rapeseed oil in water. The emulsion maintained its stabilityeven though during the test the concentration of the rapeseed oil fellto about 2%. Less copper soaps and deposits were produced than in test1, but a build-up on the dies and the sides of the tank was observed. Anunpleasant odour arose during the wiredrawing process. The sulphatedrapeseed oil is somewhat disadvantageous from a cost point of viewcompared with the sulphated sperm oil.

TEST 3 Wiredrawing was undertaken using a lubricant comprising 6 volumepercent of an emulsion in Water of a concentrate comprising wt. percentof the sulphated sperm oil and 25 wt. percent of the sulphated rapeseedoil and having a free fatty acid content of between 2.5 and 3.0 wt.percent, expressed as oleic acid.

The emulsion was very stable even when its concentration was allowed tofall to 4 vol. percent. Copper soap formation was markedly decreasedcompared to the lubricants used in tests 1 and 2 and the amount ofcopper fines, scum and deposit was smaller.

TEST 4- The wire was lubricated with a lubricant comprising a 6 vol.percent emulsion in water of a concentrate comprising 50 vol. percent ofthe sulphated sperm oil and 50 vol. percent of the sulphated rapeseedoil, the free fatty acid content of the concentrate being 2.5 to 3.0 wt.percent on an oleic acid basis.

Copper fines, scum and deposit were virtually absent and the surface ofthe lubricant was almost wholly devoid of discolouring from this cause.The emulsion maintained its stability (i.e. there were no substantialsigns of emulsion splitting) over 500' hours of operation with verylittle copper soap formation and the copper wire leaving the last diehad a bright, smooth surface. There was no noticeable unpleasant odourand the general performance was considered to be slightly superior tothat of the lubricant used in test 3. In addition, the lubricant wascheaper than the lubricant of test 3.

TEST 5 An emulsion for the lubrication of drawing of high conductivitycopper wire in a heavy rod drawing machine was prepared. The essentialfeatures of the machine were the provision of only nine dies to effect areduction in the wire diameter from 0.285 inch to 0.167 inch,corresponding to a reduction in cross-sectional area of the wire by 21%in each die. The speed of the wire drawn from the last die was 2500 feetper minute, and the amount of lubricant employed in the sump of themachine Was about 800 gallons. The conditions of operation at the diesfor this thicker copper wire were rather more severe than at the diesused for the thinner copper wire of tests 1 to 4. Accordingly, thetendency to form copper soaps and copper fines in the dies and themachine generally, and to cause consequential emulsion splitting, wouldbe expected to be greater than in tests 1 to 4.

The emulsion consisted of 94 vol. percent water and 6 vol. percent ofthe concentrate of 50 vol. percent sulphated sperm oil and 50 vol.percent of sulphated rapeseed oil as employed in test 4, the concentratehaving been dispersed by manual stirring into the Water.

The copper wire leaving the last die was uniformly bright and smooth andthere was virtually no scum of copper fines and only insignificantamounts of copper soap formation at the dies. However, someemulsionsplitting was observed after 2. months use, involving anaggregated working period of 250 hours, and investigation establishedthat the emulsion splitting could be avoided by ensuring a greaterdegree of dispersion of the concentrate in the water than could beachieved by manual stirring.

TEST 6 For reasons of convenience and economy, as explained above, itwas preferred to derive a higher degree of dispersion of the concentrateby incorporating a surfactant in the concentrate rather than by using amechanical stirrer.

The surfactant chosen was TRO, and a concentrate was formulated havingthe following composition:

Sulphated sperm oil-47.5 vol. percent Sulphated rapeseed oil-47.5 vol.percent TRO (sulphonated castor oil)5.0 vol. percent Free fatty acid (asoleic acid)2.5-3.() wt. percent.

The concentrate was manually dispersed in water to give a 6 vol. percentemulsion, and the wiredrawing was performed using the same machine andoperating conditions as for test 5. Over a period of 4 months,aggregating 500 working hours, no scum of copper fines or build-up ofcopper soaps was observed, and there was no emulsion splitting. Thequantity of concentrate which was added to the sump to maintain the 6vol. percent concentration of the emulsion was only 30 gallons-aremarkably small quantity for such an extended period of service underrelatively severe operating conditions.

The aqueous lubricant of the invention has been found not to attackferrous metal parts of the wiredrawing machines even over substantiallylong periods of use, and this was confirmed by laboratory tests in whichmoist air was bubbled through the emulsions of the invention for 96hours, while the emulsions were maintained at 60 C. and in contact withiron nails: no rusting of the nails was observed.

From the above, it will be seen that a concentrate of sulphated rapeseedoil and sulphated sperm oil (optionally with the inclusion of a minorproportion of a suitable surfactant, such as Turkey Red oil) gives awiredrawing lubricant emulsion which is superior to either of thesulphated oils used alone, or to previously known wiredrawinglubricants.

We claim:

1. A concentrate for use in forming an aqueous wiredrawing lubricantcomprising about 25-75 vol. percent of sulphated sperm oil and 75 to 25vol. percent of sulphated rapeseed oil.

2. A concentrate according to claim 1 in which the properties of thesulphated sperm oil, on a non-aqueous basis, are substantially asfollows:

Percent Total fatty matter by extraction About 100 Combined S 1.1-2.3Neutral oil 74-85 Free fatty acids, as oleic acid 1.1-6.0 Unsaponifiablematter 30-33 Total alkali, as NaOH 0.2-1.2

3. A concentrate according to claim 1 in which the properties of thesulphated rapeseed oil, on a non-aqueous basis, are substantially asfollows:

4. A concentrate according to claim 1 in which the sulphated oils arepresent in about equal proportions by volume.

5. A concentrate according to claim 1 in which the free fatty acidscontent, as oleic acid, is no more than about 3 wt. percent.

6. A concentrate according to claim 5 in which the free fatty acidscontent, expressed as oleic acid, is at least about 2.5 wt. percent.

7. A concentrate according to claim 1 comprising, in addition, effectiveamounts of a surfactant.

8. A concentrate according to claim 7 in which the surfactant issulphonated castor oil.

9. A concentrate according to claim 7 in which the surfactant comprisesabout 3 to 7 vol. percent of the concentrate.

10. A concentrate according to claim 9 in which the surfactant comprisesabout 5 vol. percent of the concentrate.

11. A concentrate according to claim 1 comprising about equalproportions of sulphated rapeseed oil and sulphated sperm oil, and about5 to 7 vol. percent of sulphonated castor oil, wherein the free fattyacid content, expressed as oleic acid, is from about 2.5 to about 3.0wt. percent.

12. A wiredrawing lubricant comprising a major proportion of water and aminor lubricating proportion of a concentrate in accordance with claim1.

13. A wiredrawing lubricant comprising Water and 2 to 9 vol. percent ofthe concentrate of claim 11.

References Cited UNITED STATES PATENTS 390,269 10/1888 Vogel 25249.32,176,434 10/1939 Niedercorn 252-49.5X

FOREIGN PATENTS 312,799 6/ 1929 Great Britain.

DANIEL E. WYMAN, Primary Examiner W. H. CANNON, Assistant Examiner U.S.Cl. X.R.

